Algae are highly nutritious and beneficial organisms. But apart from the various benefits. They can sometimes be harmful to humans and other living beings.
The main harmful effects of algae on humans are,
Poisonous: Some algae are poisonous as they produce harmful compounds and can cause the death of aquatic animals. Eg. Anabaena, Microcystis. Humans who consume such polluted water could have weight loss, weakness, miscarriage in women, etc.
Exposure to blue-green algae and algal toxins in higher concentrations could cause various symptoms in humans. The common symptoms include diarrhea, nausea, or vomiting; irritation in the skin, throat, and eyes, and eye or throat irritation. There could also be allergic reactions such as breathing difficulties. Recreational exposure from swimming, fishing, or washing could all lead to these problems.
Shellfish poisoning: Dinoflagellates are found to secrete saxitoxin which is fatal for marine animals. Shellfish are contaminated with these toxins. Those who consume such shellfish could end up having paralytic shellfish poisoning or neurotoxic shellfish poisoning, both are highly serious conditions.
Fouling of ships: The excessive growth of algae in the ocean can slow down the movement of ships. Sargassum is the best example of this. The submerged metallic parts of the ships could undergo corrosion under these circumstances.
Block photosynthesis: Epiphytic algae that grow on trees and plants can block photosynthesis in their host. This causes the eventual death of these hosts. The parasitic algae Cephaleuros virescens causes red rust in tea plants leading to economic loss in Darjeeling tea and Assam tea.
Water contamination: Algal blooms of platonic algae in the ponds and reservoirs make the water unfit for human usage. The excess growth of blue-green algae in the pipelines chokes the plumbing and water tanks, causing a foul smell, fishy taste, and discoloration of water body. Human exposure to such contaminated water could lead to symptoms such as digestive issues, allergic reactions, breathing problems, etc. On the other hand, pets and other livestock could also suffer various illnesses that could even lead to their death as well.
Mechanical injury: The excess growth of filamentous algae can cause mechanical injury to the fish in aquaculture. It can cause huge losses with the death of such animals.
Possible Questions
Explain toxic algae and describe its role in human life.